The present invention relates generally to medical devices and methods, and more particularly to catheter devices and methods that are useable to form channels (e.g., penetration tracts) between vessels such as arteries and veins and vessels and other anatomical structures, in furtherance of a therapeutic purpose such as bypassing an arterial blockage, delivering therapuetic agents, or performing other interventional procedures.
Atherosclerotic cardiovascular disease remains a major cause of premature death and morbidity, in most regions of the world. Various transluminal, catheter-based interventional techniques have been used, or proposed for use, to dilate or otherwise treat atherosclerotic obstructions that occur in coronary and/or peripheral arteries. These therapies have traditionally focused on treating the disease intraluminally, or from xe2x80x9cwithinxe2x80x9d the vessel lumen.
Included among the newer interventional techniques are certain percutaneous, transluminal techniques for bypassing obstructions in coronary or peripheral arteries through the use of the adjacent vein(s) as in situ bypass conduit(s); (e.g. using catheters to perform extra luminal procedures outside the diseased vessel lumen. These procedures are described in U.S. Pat. No. 5,830,222 (Makower) and in published PCT Applications WO 98/16161 and WO 98/46119. As described therein, in some instances, these procedures may be performed by a venous approach wherein a tissue penetrating catheter is inserted into a vein and the desired passageway or puncture is initially formed by facilitating the passage of a tissue penetrator (e.g., a flow of energy or an elongate penetration member) from a catheter, through the wall of the vein in which the catheter is positioned, and into a target location such as the lumen of an adjacent vessel (e.g. the artery). Alternatively, some of these procedures may be performed by an arterial approach wherein the catheter is inserted into an artery and the desired passageway or puncture is initially formed by facilitating the passage of a tissue penetrator (e.g., a flow of energy or elongate penetration member) from the catheter, through the wall of the artery in which the catheter is positioned, and into the target location such as the lumen of an adjacent vessel (e.g. a vein). It is typically necessary for the tissue-penetrating catheter to be placed in proper rotational orientation within the blood vessel, prior to facilitating the passage of the tissue penetrator therefrom, to ensure that the tissue penetrator is aimed or positioned to enter the target. To facilitate such aiming of the tissue penetrator, some of the previously described tissue penetrating catheters have included a penetrator direction marker that indicates the direction in which the tissue penetrator will pass from the catheter and an imaging catheter lumen through which a separate intravascular ultrasound imaging catheter (IVUS catheter) can be advanced. After the separate IVUS catheter has been advanced into the imaging lumen of the tissue penetrating catheter, the IVUS is used to image the target and the penetrator direction marker. The catheter can then be rotated within the blood vessel until the penetrator direction marker is aligned with the target, thereby indicating that subsequent advancement of the tissue penetrator from the catheter will result in the formation of the desired penetration tract between the blood vessel in which the catheter is positioned and the target.
Applicant has determined that, in cases where the tissue-penetrating catheter is to be placed in a relatively small blood vessel such as branches of the coronary artery, carotid arteries, or smaller vessels located in the peripheral vasculature (e.g. vessels in the arms or legs), it is desirable for the tissue penetrating catheter to be of reduced profile while still having sufficient column strength and torque transfer properties to allow the operator to rotate and maneuver the distal end of the catheter within the patients body by twisting, pushing and pulling the proximal end of the catheter that remains outside of the patient""s body. Thus, because the provision of a separate imaging catheter lumen substantially increases the required diameter of the tissue penetrating catheter, it is desirable to devise new tissue penetrating catheter designs that do not include an imaging catheter lumen while still maintaining the capability of imaging from a vantage point near the catheter""s distal end to facilitate proper rotational orientation of the tissue penetrating catheter to facilitate aiming of the tissue penetrator.
This invention facilitates accurate and reliable orientation of a tissue penetrating catheter in a blood vessel so that an adjacently located blood vessel or other anatomical target can be accurately penetrated, while eliminating the need for formation of a separate imaging lumen within the tissue penetrating catheter. Thus, because the need for an imaging lumen has been eliminated, the tissue penetrating catheters of this invention may be of reduced profile (e.g., 5-7 French diameter).
In accordance with the invention, there is provided a tissue penetrating catheter device that comprises an elongated catheter having an instrument lumen to facilitate the passage of a tissue penetrator, a penetrator direction marker, and an integral imaging transducer (e.g., an IVUS transducer). To facilitate orientation, the imaging transducer is useable to provide an imaging signal from which an image of the target structure and other adjacent anatomical structures can be obtained. The imaging transducer is fixedly mounted on or within the catheter, thereby eliminating the need for a separate imaging lumen which requires sufficient clearance in the lumen to allow a separate imaging transducer to be advanced and retracted in the lumen. This in turn enables the catheter to be of smaller cross sectional area. In addition, by fixedly mounting the imaging transducer on the catheter, its orientation relative to the catheter and certain components on the catheter can be specifically known.
One advantageous approach to imaging is to employ an imaging transducer which includes a plurality of imaging elements fixedly mounted on the catheter to provide an imaging signal from which an image of adjacent structures can be obtained. The imaging elements are mounted on the catheter at known circumferential locations relative to the path that will be followed by the tissue penetrator as the tissue penetrator exits from the catheter. The image obtained from the imaging signal from the imaging transducer is useable by the operator to rotationally orient the catheter such that, when the tissue penetrator subsequently exits the catheter, the tissue penetrator will extend into the desired target. In addition, the imaging transducer is useable to image other structures to allow several diagnostic functions such as assessing calcification of a vessel, distance of the target location to the vessel in which the catheter is positioned, and the presence of other devices.
Another advantageous approach to imaging is to provide an imaging marker on the catheter to form, on the image obtainable from the imaging signal from the imaging transducer, a penetrator path indication. This penetrator path indication is indicative of the path that will be followed by the tissue penetrator when the tissue penetrator exits from the catheter. The imaging transducer and the marker are useable in cooperation with each other to enable the operator to rotationally orient the catheter until the penetrator path indicator is aimed at the target thereby indicating that when the tissue penetrator exits from the catheter it will extend to the target as desired. The imaging elements fixedly mounted on the catheter at known circumferential locations can also be used to orient the catheter without any imageable markers.
When an imageable marker is used, it preferably includes a structure formed on the catheter including at least one longitudinal member disposed circumferentially about a hollow interior space. When a plurality of longitudinal members is employed, said longitudinal members are disposed at circumferentially spaced apart locations about a hollow interior space thereby forming a cage. At least one of such longitudinal members is located at a circumferential position that is axially aligned with the path or plane of the path that will be followed by the tissue penetrator as it exits from the catheter.
The tissue penetrator may be any instrument for penetrating the target of interest. For example, the tissue penetrator may be or include a laser beam, flow of energy, or an instrument which will itself puncture or penetrate the target of interest. One preferred form of tissue penetrator includes a needle member formed of resilient material that is biased to a preformed curved configuration with the needle member being initially disposed in a retracted position within the catheter and subsequently advanceable from the catheter to an extended position wherein the needle member assumes its preformed curved configuration.
The imaging transducer of the current invention is preferably an ultrasound imaging transducer and more preferably a phased array transducer. Because the phased array transducer can be fixed in a permanent manner on or within the catheter body, said phased array transducer has the advantage of being useable with or with out an imageable marker to obtain reliable and accurate orientation. Moreover, the nature of the imaging elements and the fact the imaging signal can be transmitted by multiplexing numerous signals on fewer lead wires contribute to the small profile of the catheter.
The catheter may include an elongated catheter body having a proximal end, a distal end and a peripheral wall with at least a distal region of the catheter body being flexible enough to navigate through the coronary vessels. The catheter body has an penetrator lumen that terminates distally at an exit location on the peripheral wall and contains or is adapted to receive an instrument or other tissue penetrator for penetrating the blood vessel in which the catheter body is received (xe2x80x9cresident blood vesselxe2x80x9d) to a target adjacent to the resident blood vessel. The phased array transducer is preferably an onboard transducer which is mounted on or within the catheter body and is inseparable or not removable from the catheter body. The phased array transducer is carried by the catheter body in fixed relationship to the catheter body and in some instances, in a known orientation relative to the exit location. The phased array transducer provides an imaging signal for use in locating the target and identifying the angular orientation of the exit location. Accordingly, with the penetrator received in the penetrator lumen the catheter body can be rotated to properly orient the exit location so that the penetrator can penetrate the resident blood vessel into which the catheter body is receivable and into the target. The catheter body is of sufficiently small profile so that it can be received within a coronary artery, branch or peripheral vessel if desired.
The catheter may be considered as including an imageable marker which may include a plurality of circumferentially spaced imageable members carried by the catheter body in a known circumferential orientation relative to the exit location. The imageable markers can be sensed by the phased array transducer and used to locate the target and in identifying the angular orientation of the exit location.
The phased array transducer may comprise a plurality of imaging elements arranged on the catheter body with at least one of the elements being at a known circumferential location relative to the exit location so that such at least one element is useable to identify the angular orientation of the exit location. Alternatively or in addition thereto, the at least one element may form an image region that defines an acceptable zone of penetration for the tissue penetrator.
In a preferred construction, the catheter body includes a major section which includes a proximal end and the exit location and a distal tip section extending from the major section to the distal end. The distal portion of the distal tip section has a smaller cross sectional area than the adjacent region of the major section. An active imaging apparatus is carried by the catheter body and includes imaging elements fixedly mounted on the distal tip section and a lead or leads extending proximally from the imaging elements along the catheter body. Accordingly, the reduced diameter portions of the catheter body are used to mount the imaging elements, to thereby minimize the profile of the catheter at this region of the catheter. Although various constructions are possible, in one preferred form of the invention, the major section terminates distally in a distal opening and a proximal portion of the distal tip section is received in the distal opening and a distal portion of the distal tip section extends distally of the distal opening.
The method of this invention includes inserting and transluminally advancing the catheter of this invention into a first blood vessel, actuating the imaging transducer and moving the catheter within the first blood vessel until the penetrator path indication is aimed at the target, and thereafter facilitating the exit of the tissue penetrator from the catheter through the wall of the first blood vessels and into the target. Thereafter various procedures may be performed such as the delivery of therapeutic agents or diagnostic devices.
In procedures where it may be advantageous to perform subsequent procedures over a guidewire, such as the formation of passageways between a first blood vessel and a target, the method may also include advancing a first crossing guidewire through the lumen of the tissue penetrator and into the target, such as the lumen of the second blood vessel or other target and retracting the tissue penetrator into the catheter leaving the first crossing guidewire in place.
In some procedures, such as those novel procedures more fully described in U.S. Pat. No. 5,830,222 and in U.S. patent applications Ser. Nos. 08/730,496, 09/048,147 and 09/048,147, and other means of revascularizing oxygen starved tissues or delivering therapuetic substances to vessels, tissue and other organs, it may be advantageous to obtain a second point of access to the same vessel into which the catheter was initially introduced at some point distal of the first crossing. However, this access may be limited due to the presence of calcium or other vessel disease blocking the lumen of the vessel. To obtain catheter access to a second point, distal of a diseased section in the same blood vessel, the first crossing guidewire is removed from the lumen of the tissue penetrator and reintroduced into the main guidewire lumen of the catheter and the catheter may be readvanced over the first crossing guidewire to a position wherein the catheter extends through the lumen of the first blood vessel, and through the openings created in the walls of the first and a second blood vessel. Thereafter, the catheter can be advanced distally in the lumen of the second blood vessel. To gain access back to the first blood vessel at a different location (e.g. past the disease or obstruction), the imaging transducer is actuated and the catheter is moved within the second blood vessel as required to cause the penetrator path indication to be aligned with the lumen of the first blood vessel. The tissue penetrator is advanced from the catheter through the wall of the second blood vessel and through the wall and into the lumen of the first blood vessel. To obtain guidewire access to the first blood vessel, a second crossing guidewire is advanced through the lumen of the tissue penetrator and into the lumen of the first blood vessel. The tissue penetrator is retracted into the catheter leaving the second crossing guidewire in place such that it extends from the lumen of the first blood vessel into the lumen of the second blood vessel and back into the lumen of the first blood vessel.
As part of the invention envisioned herein, a radial expandable connector can be used to provide a blood flow passageway between the blood vessels. For example, a connector delivery catheter can be advanced over the second crossing guidewire and the connector implanted such that the connector extends from the lumen of the first blood vessel through the openings created in the walls of the first and second blood vessels through the lumen of the second blood vessel through the openings created in the walls of the first and second blood vessels and back into the lumen of the first blood vessel.
The invention together with additional features and advantages thereof may best be understood by reference to the following description taken in connection with the accompanying illustrated drawings.